1. Field of the Invention
The present invention relates to speed control mechanisms for internal combustion engines and more particularly to a holding device for an engine speed control lever or throttle of an earth moving apparatus, such as a farming implement or a grader. Typically such vehicles have been provided with hand throttles which can be preset at a fixed position for operation of the vehicle. However, if an emergency situation developed, the vehicle operator had to manually close the throttle before applying the brake. Because such an arrangement prevented the vehicle operator from acting quickly enough when confronted with a panic stop it was proposed to replace the preset hand throttle with a resiliently biased foot pedal which was under the constant control of the operator. However, because of considerable forces exerted by the foot pedal and the need to keep such foot pedal depressed for long periods of time, it has become necessary to provide means associated with the foot pedal for retaining the throttle in a fixed position, as well as means for releasing the throttle when an emergency situation occurs.
2. Known Systems
Various means have been devised for controlling the speed of a vehicle. For example, U.S. Pat. No. 3,437,182 issued Apr. 8, 1969 to Mueller provides a governor for controlling the speed of a vehicle as well as means for adjusting the governor so as to increase or decrease speed as well as control deceleration of the vehicle. However, the apparatus disclosed by Mueller includes an elaborate vacuum assisted unit and generally represents a rather complex means for controlling the speed of a vehicle.
A second method is provided in U.S. Pat. No. 3,164,219 issued Jan. 5, 1965 to Orr. The Orr patent combines a hydraulic actuator with a series of complicated mechanical linkages and a frictional device for controlling the speed of a vehicle as well as controlling acceleration and deceleration of the vehicle.
The mechanisms disclosed by the foregoing patents are relatively complex, displaying multiple apparatus within a single system, such apparatuses including complicated mechanical linkages as well as relatively complex hydraulic or vacuum assisted devices requiring specialized manufacturing techniques and produced only at considerable expense. There exists a need for a relatively simple device for controlling the throttle of an internal combustion engine.